Box patched its systems hours after learning about the bug last week. It also revoked and reissued its SSL certificates.

The technology industry went into emergency mode last Monday when it was revealed that a severe flaw existed since December 2011 in several versions of the OpenSSL cryptographic library used by millions of websites to encrypt their communications via SSL (Secure Sockets Layer) and TLS (Transport Layer Security). The flaw was patched on Monday.

Since then, companies that provide services via their websites have been scrambling to patch servers, because, if exploited, the flaw could allow an attacker to monitor information exchanged between end users and the affected systems and steal critical data.

Box is strongly suggesting that its customers turn on two-factor authentication and requiring that its users set strong passwords. The company is also encouraging customers to configure the single sign-on capability if they use Box with partners’ third-party software that has been pre-integrated with Box.

Box has about 25 million registered users, of which about 1.75 million use a paid version of the service via corporate or individual accounts. The company has about 34,000 paying corporate customers, including more than 40 percent of the Fortune 500 and 20 percent of Global 2000 companies.

The Los Altos, California, company, founded in 2005, announced in March that it plans to go public.

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